Lateral rocker arm movement

These are Comp Cams Magnum rockers. I looked, that wansn't a crack, but good catch, it does look like one. Whatever it was it wipped away. The retainers are by Crane. This motor is 11 years old but has about 10 miles on it. The others don;t have that bid of gap, just the top photo of the number 1 valvetrain.